Transmission system



May 10, 1932. w. T. REA 9 1,857,258

TRANSMISSION SYSTEM Filed May 9, 1931 MEZjZ B E 5i? ATTORNEY Patented May 10, 1932 UNITED STATES PATENT orrics WILTON T. REA, OF FLUSHING, NEW YORK, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK TRANSMISSION SYSTEM Application filed May 9,

This invention relates to telegraph systems, and more particularly to improved arrangements whereby signals may be originated and received on such'systems at a high 5 signaling speed and whereby such high speed signals may be transmitted between stations over lines suitable only for low speed signals.

To distinguish between low speed and high speed telegraph signals and low speed and 1.0 high speed telegraph lines for the purpose of this invention, it is pointed out that the speed of the signals may be defined as the number of dots or impulses originated per second. The shortest impulse of a set of mes- 15 sage impulses would be utilized to fix the maximum speed of the message signals. The number of these shortest impulses that could be transmitted per second could be termed the speed of the signals or could becharacterized as the maximum fundamental frequency of the signaling current.

A telegraph line interconnecting two stations would usually have associated therewith certain selective devices, such as filters or composite sets, and these filters or composite sets might be designed to cut off frequencies above 60 to 7 0 cycles. Accordingly, such a circuit would be suitable for the transmission of telegraph signals having a maximum speed of 60 to 70 impulses per second or, in other words, for a signaling current below such frequencies. This type of circuit might, for the purpose of illustrating this invention, be termed a low speed telegraph circuit. Obviously, it may be de: sirable to originate and receive signals at a speed faster than 60 to 70 impulses per second and this would result in the utilization of a current of a higher frequency. The use of a higher frequency current would not be possible on the type of circuit heretofore termed a low speed circuit because of the cut-off characteristics of the filters or other apparatus associated with the line. Accordingly, to accommodate high speed signals, the filters or other devices in the line would have to be redesigned to have a higher frequency cutoff? characteristic so that the line might be termed a high speed circuit. Obviously, this would necessitate the reconstruction or re- 1931. Serial No. 536,287.

design of the low speed circuit into a high speed circuit.

One of the primary objects of the arrangements of the invention is to make it possible I to utilize the low speed circuit without any change therein for thetransmission of high speed telegraph signals. 1n the arrangements of the invention this is accomplished by resolving a series of high speed signals into a plurality of series of signals of approximately half the original frequency. The signals of this lower frequency -may then be transmitted over a pluralityof low speed telegraph circuits and may be recombined at the other end of the line to form the I In Fig. 1 is shown a telegraph system in which two stations are interconnected by the lines L and L These lines might be used for both telephone and telegraph purposes and would have included therein selective devices, such as filters, or the composite sets 20, 21, 22 and 23. Circuits 16, 17, 18 and 19 might be telephone circuits. If the lines L and L; were use as composited telephone and telegraph lines, the selective devices might be designed to have a cut-off frequency characteristic of 60 or 70 cycles, and accordingly,-

telegraph signals having a greater speed than 60 or 70 dots per second, or 111 other words,

requiring a signaling current with frequency above 60 or 70 cycles, could not be sent over such lines. Lines of this type may, for the purpose of illustrating this invention, be termed low speed telegraph circuits. At the sending end of the system there is associated with the low speed telegraph lines a combination of relays A, B, and C. The relay C winding;of relay A to. ground 14.

.binationA', B, O will resolve this-series-of hi h speed signals intotwo series of signals of a lower frequency suitable for transmission over lines L and L At thereceiv-ing end of the line the relay combination DE will recombine the transmitted signals to formv the original high speed signals.

The operation of Fig. 1 is asfollows:

The sending loop 1 includes the key K and the winding of the relay 0. When the key Kis open the relays A, B, and C will. be re- .leased as shown in the drawings. Under these conditions relays D and E, which are connected to relays A and B by the lines L and L respectively, will also be released 51 andno current will flow in the receiving loop 12.1nto which is connected the sounder When .thekey Kis closed for the first time,

current willfiow. through the winding of re-- lay. C,.operat1ng 1t. When-relay C operates the following circuit will be closed: Battery 13,,back. contact of relay B, armature and contact-of relay C,.back contact of relay B,

The clo ing of this circuit will operate relay A. When relay A= operates the battery 13 will be con- .nected over the lefthand contact of rela Y A andthro-ughthe winding: of relay B to the battery '15. The batteries-13 and -will opp oseeach other in thewinding' of relay B .and relay B will not operate-at this time. The

operation of relay A will. close-the line circuit L and operate-the relay D. The operation of relay D will close the receiving loop 12 and operate thesounder S.

Thus it will be seen that when. key K is 'closed for the first: time, operating. current willbe transmitted over the line L and relay D will be operated. At the same time operating current will not be applied to line L and relay E will not be operated. Under these conditions the sounder S will'operate.

If the key K is now opened, the battery 13 will be removed from one terminal of the winding of relay B. A current will flow from battery 15 through the winding of relay B, left-hand contact of relay A, winding of relay A to ground 14. This will operate relay B and hold relay A operated. The operation of relay B will close the line circuit L and cause operating current to be transmitted over said line to operatethe relay E. The operation of relay E will open circuit 12 and-release the sounder S. 1

Thus it will be seen that when the key K is opened for the first time in the cycle of operations, that the relay E will be operated. The relay D had previously been operated by the first closing of the key K. Under these conditions the sounder S is released.

When the key K is closed for the second time the following circuit will be completed. From ground 14, right-hand front contact of relay B, armature and contact of relay C, left-hand front contact of relay B winding ofrelay B to battery 15'. This will hold relay B operated but will short-circuit the winding of relay A and cause relay A to release. The release of relay A will release relay D. This will close the receiving loop circuit 12 and operate the sounder S.

Thus it will be seen that when the key Kv is closed for the second time in the cycle of operations thatthe relay I) will. hereleased. The relay-E is in the meantime held operated. Under these conditions the sounder S will operate.

lVhen the key K is again opened, ground will be removed from the windingof relay B, allowing it to releaseand returning'all the relays to the conditionshown in the drawings. This willrelease the sounder S.

Thus'it'willbe seen that the sounder S will follow the movement of the key K.

,In. Fig. '2 is shown a modification of the arrangements "of the invention. This figureshows a telegraph repeater: circuitembodying the invention. In this circuit .fivepolar relays R ,,R R5, R and R are substituted for therelaysA and B of Fig. 1. Relays R and R correspondto-relays D. and E of. Fig. l.

The operation of the arrangements of Fig. 2 isas follows: The closing. of key K in'the sending loop circuit 1 for the purpose of signaling will operate relay R: and cause, it"

to close its armature and contact. This will close the following circuit: Negative pole of battery B contact and-armature of: relay R conductor 2, armature and contact of relay R conductor 3, contact of relay R conductor- 4, windings of relays R and R to ground 31. This will'operate relays R and R The operation of relay R will connect the negative pole of battery B from the previously traced circuit over the contact and-armature of relay R and thence through 'the windings of relays R R and R to the negative pole'of battery B As the polarity of batteries B and B are alike, relays R B and R will notoperate at this time. The aforementioned operationof relay B will close a circuit froinbattery B armature and contact of relay R o er conductor 5 through the winding of relaylft to batterjnand will operate relay B The operation of relay R, will apply current over the line L to operate relay R The operation of relay R will close circuit 12 and operate the sounder S.

Thus it will be seen that the operation of key Kfor the first time willcauseoperating current to be transmitted over line L to operate relay R At the same time no operating current will be transmitted over line L and relay R is not operated. Under these conditions the sounder S is operated.

The opening of key K will now release relay R and open the previously traced circuit completed over the contact and armature of relay R This will disconnect the negative battery B from the windings of relays R R and A circuit will now be completed for these relays as follows: From negative battery B windings of relay R R and R armature and contact of relay R conductor 4, windings of relays R and R to ground 31. This will operate relays R R and R and will also holdoperated relays B and R The operation of relay R will close a circuit from battery B armature and contact of relay R conductor 6, windings of relay R to battery, thus operating relay R The operation of relay R will apply operating current to the line L and operate relay R This will open circuit 12 and release sounder S.

Thus it will be seen that the opening of key K for the first time in the cycle of operation will cause operating current to be transmitted over line L and will operate relay B As has been pointed out, operating current is 1 at the same time being transmitted over line L and is holding relay R operated. Under these conditions the sounder S is released.

When the key K is again closed, therelay R will be operated and the following circuit closed: From ground, contact and armature of relay R conductor 2, armature and contact of relay B conductor 3, armature and contact of relay R windings of relays R R and R to battery B This will hold relays R R; and R operated and will short-- circuit to ground the previously closed operating circuit for relays R and R and will release these relays. The release of relays R and B- will open the previously closed circuit from battery B over conductor 5, for relay R and will release the latter relay. The release of relay R will reverse the operating current in line L and release relay R This will again operate sounder S.

Thus it will be seen that the closing of key K for the second time in the cycleof operation will reverse the operating current in line L and release relay R As has been pointed out, operating current is at this time being applied to line L and relay R is operated. Under these conditions the sounder S is operated.

hen the key K is again opened the relay R is released and opens at its armature and contact the operating circuit previously traced from ground and the contact of relay R for the relays R R. and R thus releasing these relays. The relays R and R will remain released. The release of relay R will open the-previously traced circuit froin-battery B overconductor 6, for relay R and will releasethelatter relay. The release of relay R will reverse the operating current in line L and will release relay This will open circuit 12and'release sounder S.

Thus it will be seen that the opening of key Kfor the second time in the cycle of operation will disconnectoperatingcurrent from line L and release relay R As has been pointed out, operating current is at this time disconnected from line L and relay R13 is released. Under these conditions the sounder S is released.

It will thus be seen that the operation and release of'the sounder S corresponds with the closing and opening, of the signaling key K.

In Fig. 3 is shown a modification of the relay arrangements A, B, G, of Fig. 1. In the modification two polar relays A and B having more than two windings may be used to control the lines L and L in place of the relays A,"B and C. i

'.The operation of the arrangements of Fig. 3 is as follows: The operation of key K'will close the following'circuit, from ground, key K, conductor 47, spacing Contact of relay B, conductor 48, winding 40 of relay A, conductor'49, to battery 46. This will operate relay A and close circuit L Relay B will .not operate at this time as its winding 43 will be short-circuited to ground. lVhen key K is opened again the short circuit to ground over contacts of key K will be removed from winding 43 and relay B will operate and closeline L ,When key K- is closed for the second time a circuit will be closed from ground, key K, conductor 47, marking contact of relay B, conductor 50, and in parallel through windings 41' and 44 of relay A and B, to battery 46. The effect of this current on relay A tends to move its armature to the spacing contact and cancels the effect of the current in winding 40. Relay A"therefore releases cuits. By varying the relay combinations at the sending and receiving ends of the transmission system a greater number of circuits may be utilized in the combination if necessary'. The principles of the intention may furthermore be utilized in connection with secret transmission systems, since the transmitted signal is not understandable except in thepresence of all of its components. The

arrangements of the invention may be utif lized on lines which doun'ot include .filters or 'composite'setsif the frequencycharacteristics ofthe linesthemselvesmake it;desirable.. The

arrangements of the invention are furthermore applicable to other'types of'telegraph systems from those illustrated, suchfor: example as carrier telegraph systems.

While the invention has been disclosedas cmbodied'incertm'n specific forms'which are i q deemedv desirable, .itis :understoodathat; it'ris capable of embodiment in manyiand other Widely varied forms without ClBPZLIftlllgfI'OIH the spirit: of. the invention as defined: by the appended claims.

What is claimed-is:

' 0 so that the maximum frequencyof the signal impulses onthe lines is less than'themaximum frequency of the signal impulses in the loop, said means consisting of a. relayiarrangementiconsisting-o'fxtwo relays each of which 1 controls the frequency of application of signals applied to diiferent ones of said lines, a circuit for operatingsaid relay arrangement completed solely over the contacts ofsaid'relays and said sending loop'andcontrolledby in the signals originated 'inxsaid sendingloop,

and relay means :in each of said transmission lines for jointly controlling: said receiving I loop.

'2'; 'Aztelegrapli system comprisingjasenda. ing loop and a receiving loop,.two transmission lines, and means for transmitting the signals originating in said loop over said. lines sothat.- themaximum frequency of the signal impulses onthe lines will be less than the 40 maximum frequency ofthe signal impulses-in the loop, saidmeans consisting; of two' relays each of which controls the frequency of .application of signaling current to said lines, a circuit for said relays completed solely. over the; contacts ofsa-id relays and said sending loop and controlled-by the operationoffsaid sendingloop, saidcircuit forsaidvrelays being so arranged that when the sendingv loop is closed for the first time one of said relays will operate, when the sending loop is next opened both of said relays will be operated, when the sending loop isnext closed the first of saidrelays to be operatedwill be released, and when the sending'loopis next'opened both of: said relayswill be released, and relay means-controlled icy-each of saidxtransmiss'ion lines for jointly controllingsa-id: receiving loop.

3. The combination of a high speedtelegraph circuit with two low speedtelegraph circuits, and a translating device for resolving the high speed signals originatingin said high speed circuit into two seriesof lowspeed-signals for transmission over said low speedrcircuits, said translating device consisting; of a over thecontacts of said relays and said sending loop and controlled by the operation of said sending loop, said circuit arrangement ing loop is closed for the first time a circuit for the first of said relays will be closed and a'circuit for the second of said relays will be prepared by the operation of said first relay,

rent to different ones of'said lines, a circuit arrangement for said relays completed solely for saidrela'ys being ch that when the send- 380 when the sending loop is next opened said circuit prepared for said second relay will become operative and a-holding circuit will be completedior said first relay, when said sending loop 1s next closed the holding circuit for said first relay will be short circuited-and said firstrelay released and another operative circuit completed for said second relay, when said sending loop is next opened said last mentioned operative circuit for said second relay will be opened, and relay means controlled by each of said transmission lines for jointly controlling said receiving loop.

5. A telegraph system consisting of a sending loop and a receiving loop, two transmission lines, two relays each of which controls the frequency of application of signaling current to different ones of saidlines, operating cricuits for eachof said relays, a plurality of polar relays for controlling'said operating circuits, control circuits for said polar relays separate from said operating circuits completed over the contacts of saidpolar relays and the contacts ofsaid sending loop and relay means controlled by each of said trans mission lines for jointly controlling said receiving loop.

6. A' telegraph system consisting of a sending loop and a receiving loop, two transmission lines, two relays each of which controls the frequency of application of signaling current to different ones of said lines, operating circuits for each of said relays, a plurality of polar relays for controlling said operating circuits, control circuits for said polar relays separate from said operating circuits completed over the contacts of said polar relays and the contacts of said sending loop said control circuits being so arranged that when the sending loop is first closed a circuit will be completed for one group of said polar relays and the operating circuit for the first of said two first mentioned relays'will be closed and a circuit will be prepared for a second group of said-polar relays, when the sending loop is next opened said prepared circuit will become operative and the second group of said polar relays will operate and close the operating circuit for the second of said two first mentioned relays and a short circuit will be prepared for said first group of polar relays, when the sending loop is next closed said short circuit for said first group of polar relays will become efiective and said relays will release and open the operating circuit for the first of said two first mentioned relays and a holding circuit for said second group of polar relays will be completed, when said sending loop is next opened said holding circuit for said second group of polar relays will be opened and said relays will release and open the operating circuit for the second of said two first mentioned relays, and relay means controlled by each of said transmission lines for jointly controlling said receiving loop.

7. A telegraph system consisting of two transmission lines, two multi-winding polar relays each of which controls the frequency of application of signaling currents to different ones of said lines, and signaling circuit arrangements controlled by switching means for controlling said polar relays, said signaling circuit arrangements comprising means operable when said switching means is first closed for completing a circuit through a winding of thefirst of said relays whereby it will operate and for preparing a circuit through a winding of the second of said relays, means operable when said switching means is next opened for render ing said prepared circuit for said second relay operative to operate said relay and to complete a holding circuit for said first relay, means operable when said switching means is next closed for completing parallel circuits through additional windings of each of said relays whereby the direction of current flow in the additional winding of said first relay will be opposed to the current flow in the other winding thereof and said relay will release and whereby the direction of current flow in the additional winding of said second relay will aid the current flow in the other winding thereof and said relay will remain operated, and means operable when said switching means is next opened for releasing said second relay.

8. A telegraph system consisting of two transmission lines, two multi-winding polar relays each of which controls the frequency of application of signaling currents to different ones of said lines, switching means, and means controlled by successive operations of said switching means for successively completing the following circuits, an operating circuit including a winding of one of said relays, an operating circuit including said winding of said first relay and a winding of a second relay, a circuit including in parallel other windings of each of said relays so poled May 1931.

WILTON T. REA. 

